Use the search function. It's at the top manu.
If you have doubt about a topic then use ab keyword/word and search with it. Selecting time range is handy. You can also the option of ordering your search. My preference is "Most recent topic first"
Yes OP, do as @Royse777 says.
There is another alternative. I do pretty much the same using google. I can show results from bitcointalk.org only if you set it like that. Then you can also set time interval preferences and so on.
But don't be too worried about it, just search a bit before creating a thread.